Display panel and display device

ABSTRACT

According to one embodiment, a display panel includes a substrate, a switching element, a pixel electrode, an organic light emitting layer, an opposite electrode, a detecting electrode, and an insulating layer. The substrate has a major surface. The switching element is provided on the major surface. The switching element includes a semiconductor layer. The pixel electrode is provided on the major surface. The pixel electrode is electrically connected to the switching element. The organic light emitting layer is provided on the pixel electrode. The opposite electrode is provided on the organic light emitting layer. The detecting electrode is provided between the substrate and at least a part of the pixel electrode. The detecting electrode includes at least one element included in the semiconductor layer. The insulating layer is provided between the pixel electrode and the detecting electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2012-095914, filed on Apr. 19,2012; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display panel and adisplay device.

BACKGROUND

There are an active matrix display panel in which a current passingthrough an organic EL (Electro-Luminescent) device is controlled by athin film transistor and a display device using the display panel. Insuch a display panel and a display device, it is desired to provide adetection function to detect a touch manipulation. In the case ofproviding the detection function, an aperture ratio is reduced, andimage quality is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are schematic views illustrating the configurationof a display panel according to a first embodiment;

FIG. 2 is an equivalent circuit diagram illustrating the configurationof the display panel according to the first embodiment;

FIG. 3 is an equivalent circuit diagram illustrating the configurationof the display panel according to the first embodiment;

FIG. 4 is a graph illustrating the characteristics of the display panelaccording to the first embodiment;

FIG. 5 is a schematic view illustrating the configuration of a displaydevice according to a second embodiment; and

FIG. 6 is a timing chart illustrating a part of the control of thedisplay device according to the second embodiment.

DETAILED DESCRIPTION

According to one embodiment, a display panel includes a substrate, aswitching element, a pixel electrode, an organic light emitting layer,an opposite electrode, a detecting electrode, and an insulating layer.The substrate has a major surface. The substrate is light transmissive.The switching element is provided on the major surface. The switchingelement includes a semiconductor layer. The pixel electrode is providedon the major surface. The pixel electrode is electrically connected tothe switching element. The pixel electrode is light transmissive. Theorganic light emitting layer is provided on the pixel electrode. Theopposite electrode is provided on the organic light emitting layer. Thedetecting electrode is provided between the substrate and at least apart of the pixel electrode. The detecting electrode includes at leastone element included in the semiconductor layer. The detecting electrodeis light transmissive. The insulating layer is provided between thepixel electrode and the detecting electrode. The insulating layer islight transmissive.

According to another embodiment, a display device includes a displaypanel and a control unit. The display panel includes a substrate, aswitching element, a pixel electrode, an organic light emitting layer,an opposite electrode, a detecting electrode, and an insulating layer.The substrate has a major surface. The substrate is light transmissive.The switching element is provided on the major surface. The switchingelement includes a semiconductor layer. The pixel electrode is providedon the major surface. The pixel electrode is electrically connected tothe switching element. The pixel electrode is light transmissive. Theorganic light emitting layer is provided on the pixel electrode. Theopposite electrode is provided on the organic light emitting layer. Thedetecting electrode is provided between the substrate and at least apart of the pixel electrode. The detecting electrode includes at leastone element included in the semiconductor layer. The detecting electrodeis light transmissive. The insulating layer is provided between thepixel electrode and the detecting electrode. The insulating layer islight transmissive. The control unit is configured to control anoperation of the switching element to control a light emitted from theorganic light emitting layer. The control unit is configured to detect acapacitance of a detecting capacitor formed of the pixel electrode, thedetecting electrode, and the insulating film.

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

It is noted that the drawings are schematic or conceptual. Therelationship between the thicknesses and widths of portions, a ratio ofsize between portions, or the like are not necessarily the same as realones. Moreover, even in the case of expressing the same portions,dimensions and ratios between the portions are sometimes expresseddifferently depending on the drawings.

In the specification and drawings, components similar to those describedor illustrated in a drawing thereinabove are marked with the identicalreference numerals, and a detailed description is omitted asappropriate.

First Embodiment

FIG. 1A and FIG. 1B are schematic views illustrating the configurationof a display panel according to a first embodiment.

FIG. 1A is a schematic cross-sectional view. FIG. 1B is a schematic planview. FIG. 1A schematically shows a cross section on line A1-A2 in FIG.1B.

As shown in FIG. 1A and FIG. 1B, a display panel 110 according to theembodiment includes a substrate 10, a switching element 12, a pixelelectrode 16, an organic light emitting layer 18, an opposite electrode20, a detecting electrode 50, and an insulating layer 52.

The pixel electrode 16, the organic light emitting layer 18, and theopposite electrode 20 form an organic EL light emitting element portion24. The light emission of the light emitting element portion 24 iscontrolled and driven by the switching element 12. In the display panel110, the combinations of the switching elements 12 and the lightemitting element portions 24 are disposed in a matrix configuration. Inthe display panel 110, the drive of the switching elements 12 and thelight emission of the light emitting element portions 24 in associationwith the drive are controlled to display pictures. The display panel 110is an active matrix display panel using an organic EL device.

The pixel electrode 16, the detecting electrode 50, and the insulatinglayer 52 form a detecting capacitor 70 that detects the presence orabsence of a subject to be detected, which is coming close to thedetecting electrode 50 (see FIG. 2). In the detection of the subject tobe detected by the detecting capacitor 70, a so-called touchmanipulation is implemented in which a manipulation instruction isinputted to the display panel 110 by touching a screen with a finger, adedicated pen, or the like, for example. Namely, the display panel 110is a display panel equipped with a detection function to detect a touchmanipulation (a touch panel display).

The substrate 10 has a first major surface (a major surface) 10 a and asecond major surface 10 b opposite the first major surface 10 a. Thesubstrate 10 is light transmissive, for example. In the specification, alight transmissive component means that light emitted from the lightemitting element portion 24 can be transmitted through the component.The substrate 10 is transparent, for example. A resin material such as apolyimide resin and an aramid resin, for example, is used for thesubstrate 10. Thus, a flexible display panel 110 can be implemented. Amaterial used for the substrate 10 may be an inflexible material such asa glass material and a hard resin material. Preferably, the thickness ofthe substrate 10 is thinner, 0.5 mm or less, for example.

A barrier layer that suppresses the penetration of impurities, moisture,or the like, for example, may be provided on the first major surface 10a of the substrate 10. A silicon oxide film, a silicon nitride film,silicon oxynitride film, or the like, for example, is used for thebarrier layer. Thereby, the switching element 12 and the light emittingelement portion 24 provided on the substrate 10 can be protected fromimpurities, moisture, or the like, for example.

Here, suppose that a first direction perpendicular to the first majorsurface 10 a is a Z-axis direction. A direction perpendicular to theZ-axis direction is taken as an X-axis direction. A directionperpendicular to the Z-axis direction and the X-axis direction is takenas a Y-axis direction.

The switching element 12 is provided on the major surface 10 a of thesubstrate 10.

The switching element 12 includes a first conducting portion 31, asecond conducting portion 32, a gate electrode 33, a gate insulatingfilm 34, a semiconductor layer 35, and a channel protection film 36.

The gate electrode 33 is provided on the major surface 10 a of thesubstrate 10. A high melting point metal such as molybdenum tungsten(MoW), molybdenum tantalum (MoTa), and tungsten (W), for example, isused for the gate electrode 33. An Al alloy having a principal componentof Al in which an anti-hillock configuration is provided may be used forthe gate electrode 33, for example. A stacked body of Al and a highmelting point metal may be used for the gate electrode 33, for example.

The gate insulating film 34 is provided on the gate electrode 33. Inthis example, the gate insulating film 34 is provided on throughout themajor surface 10 a so as to cover the gate electrode 33. An insulativeand light transmissive material, for example, is used for the gateinsulating film 34. A silicon oxide film, a silicon nitride film, asilicon oxynitride film, or the like can be used for the gate insulatingfilm 34, for example. The gate insulating film 34 may be a stacked bodyincluding at least one of a silicon oxide film, a silicon nitride film,and a silicon oxynitride film, for example.

The semiconductor layer 35 is provided on the gate insulating film 34.The gate insulating film 34 is provided between the gate electrode 33and the semiconductor layer 35, and insulates the gate electrode 33 fromthe semiconductor layer 35. An amorphous oxide semiconductor includingat least one of In, Ga, and Zn is used for the semiconductor layer 35,for example. Namely, one of an In—Ga—Zn—O oxide semiconductor, anIn—Ga—O oxide semiconductor, and an In—Zn—O oxide semiconductor is usedfor the semiconductor layer 35, for example. The thickness of thesemiconductor layer 35 (a length along the Z-axis direction) is about 50nm, for example. Thus, the electric characteristics of the semiconductorlayer 35 are made excellent. More specifically, the thickness of thesemiconductor layer 35 is 10 nm or more and 100 nm or less, for example.The material of the semiconductor layer 35 may be a given material thatis a light transmissive material and can control the light emission ofthe light emitting element portion 24, for example.

In the semiconductor layer 35 including an amorphous oxidesemiconductor, a diffraction pattern or the like showing crystallinityis not observed even though the semiconductor layer 35 is observed usinga transmission electron microscope (TEM) or X-ray diffraction (XRD)topography, for example. The film and shape of the semiconductor layer35 can be observed using a scanning electron microscope (SEM), TEM, orthe like.

For the semiconductor layer 35, such a material may be used that themicrocrystals of the oxide semiconductor are dispersed in the amorphousoxide semiconductor described above.

The first conducting portion 31 is electrically connected to thesemiconductor layer 35. The second conducting portion 32 is electricallyconnected to the semiconductor layer 35. Ti, Al, Mo, and the like, forexample, are used for the first conducting portion 31 and the secondconducting portion 32. The first conducting portion 31 and the secondconducting portion 32 may be a stacked body including at least one ofTi, Al and Mo, for example. The first conducting portion 31 is one ofthe source electrode and drain electrode of the switching element 12.The second conducting portion 32 is the other of the source electrodeand drain electrode of the switching element 12.

The channel protection film 36 is provided on the semiconductor layer35. The channel protection film 36 protects the semiconductor layer 35.An insulative material is used for the channel protection film 36. Asilicon oxide film, for example, is used for the channel protection film36. In the case where an amorphous oxide semiconductor is used for thesemiconductor layer 35, a silicon oxide film with acid resistance higherthan the acid resistance of the semiconductor layer 35 is used for thechannel protection film 36, for example. The channel protection film 36may be a silicon nitride film or a silicon oxynitride film, for example.

The first conducting portion 31 covers a first portion 36 a of thechannel protection film 36. The second conducting portion 32 covers asecond portion 36 b of the channel protection film 36. The firstconducting portion 31 covers a first region 35 a of the semiconductorlayer 35. The second conducting portion 32 covers a second region 35 bof the semiconductor layer 35. The second region 35 b is apart from thefirst region 53 a in a direction parallel to the first major surface 10a. The second conducting portion 32 is disposed apart from the firstconducting portion 31. The semiconductor layer 35 has a third region 35c which is provided between the first region 35 a and the second region35 b. The third region 35 c is not covered with the first conductingportion 31 and the second conducting portion 32. The gate electrode 33has a portion 33 a between the first conducting portion 31 and thesecond conducting portion 32 when seen in a direction perpendicular to afilm surface 35 p of the semiconductor layer 35 (in the Z-axisdirection). The gate electrode 33 opposes the third region 35 c of thesemiconductor layer 35 via the gate insulating film 34. The gateinsulating film 34 is disposed between the gate electrode 33 and thethird region 35 c. The channel protection film 36 is provided at leaston the third region 35 c.

A voltage is applied to the gate electrode 33 to generate a channelthrough the semiconductor layer 35, and a current passes across thefirst conducting portion 31 and the second conducting portion 32. Inthis example, the switching element 12 is a bottom gate thin filmtransistor. The switching element 12 is not limited to a bottom gatethin film transistor. The switching element 12 may be a top gate thinfilm transistor, for example. The switching element 12 may be atransistor in other structures or the like. In the bottom gatestructure, the gate electrode 33 can suppress a malfunction caused byexternal light incident to the semiconductor layer 35.

The detecting electrode 50 is provided between at least a part of thepixel electrode 16 and the substrate 10. In this example, the detectingelectrode 50 is provided on the gate insulating film 34. The detectingelectrode 50 is provided on the same surface as the semiconductor layer35 is located. A difference between a distance between the detectingelectrode 50 and the substrate 10 along the Z-axis direction and adistance between the detecting electrode 50 and the substrate 10 alongthe Z-axis direction is 10 nm or less. A distance between the detectingelectrode 50 and the substrate 10 along the Z-axis direction issubstantially the same as a distance between the semiconductor layer 35and the substrate 10 along the Z-axis direction.

The detecting electrode 50 is light transmissive. The detectingelectrode 50 is transparent, for example. The detecting electrode 50includes at least one element included in the semiconductor layer 35. Inthis example, the detecting electrode 50 includes at least one of In,Ga, and Zn. An amorphous oxide semiconductor is used for the detectingelectrode 50. One of an In—Ga—Zn—O oxide semiconductor, an In—Ga—O oxidesemiconductor, and an In—Zn—O oxide semiconductor is used for thedetecting electrode 50, for example. A material substantially the sameas the material of the semiconductor layer 35 is used for the detectingelectrode 50. The detecting electrode 50 is formed in the same processsteps as the semiconductor layer 35, for example.

The insulating layer 52 is provided between the pixel electrode 16 andthe detecting electrode 50. The insulating layer 52 is lighttransmissive. The insulating layer 52 is transparent, for example. Inthis example, the insulating layer 52 is provided on throughout thefirst major surface 10 a, and covers the detecting electrode 50 and theswitching element 12. The insulating layer 52 includes a contact layer53 and an organic layer 54. The insulating layer 52 may include one ofthe contact layer 53 and the organic layer 54. The insulating layer 52may further include another light transmissive and insulative layer.

The contact layer 53 is provided as contacting the detecting electrode50. The contact layer 53 includes at least one of a silicon oxide film,a silicon oxynitride film, and a silicon nitride film, for example. Thethickness of the contact layer 53 along the Z-axis direction (the lengthalong the Z-axis direction) is 100 nm or more and 200 nm or less, forexample. The contact layer 53 is formed by CVD (Chemical VaporDeposition), for example.

The concentration of hydrogen included in the contact layer 53 is 1×10¹⁹atoms/cm³ or more, for example. The contact layer 53 having the hydrogenconcentration can be implemented by increasing the ratio of a silaneflow rate in forming the contact layer 53 by CVD, for example. Thereby,hydrogen included in the contact layer 53 can be moved in the detectingelectrode 50 and the resistance of the detecting electrode 50 includingan amorphous oxide semiconductor can be decreased.

On the other hand, the channel protection film 36 is provided on thesemiconductor layer 35 including the same amorphous oxide semiconductor,and the channel protection film 36 suppresses the penetration ofhydrogen. Thereby, a reduction in the resistance of the semiconductorlayer 35 can be suppressed. Namely, it is suppressed that the switchingelement 12 is turned into the normally on state.

The organic layer 54 is a color filter CF, for example. The color filterCF has a different color for every pixel. The color filter CF includesone of red, green, and blue colors, for example. In the display panel110, the color filter CF having one of red, green, and blue colors, forexample, is individually disposed in a predetermined pattern for thepixels. Thereby the display of full color pictures can be enabled in thedisplay panel 110. A color resin film (a color resist, for example) isused for the color filter CF, for example. The color filter CF is lighttransmissive. The transmittance of the color filter CF is varieddepending on wavelengths.

The thickness of the organic layer 54 (the color filter CF) along theZ-axis direction is 1 μm or more 10 μm or less, for example, morespecifically, 2 μm or more. Therefore, since the parasitic capacitancegenerated between the detecting electrode 50 and the opposite electrode20 can be reduced, the sensitivity of detecting a touch manipulation canbe improved. The organic layer 54 may be a silicone resin or the like,for example. The organic layer 54 may be a material that is lighttransmissive to the light emitted from the light emitting elementportion 24 and can provide the thickness recited above.

The pixel electrode 16 is electrically connected to one of the firstconducting portion 31 and the second conducting portion 32. In thisexample, the pixel electrode 16 is electrically connected to the firstconducting portion 31 (a source, for example). The pixel electrode 16 isprovided on the first major surface 10 a. In this example, the pixelelectrode 16 is provided on the insulating layer 52. The pixel electrode16 has an opposing region 16 a opposing the switching element 12 and anon-opposing region 16 b not opposing the switching element 12 in theZ-axis direction. The pixel electrode 16 overlaps with the detectingelectrode 50 in the non-opposing region 16 b when projected onto thefirst major surface 10 a (an X-Y plane).

An electrically conductive and light transmissive material, for example,is used for the pixel electrode 16. ITO (Indium Tin Oxide), anITO/Ag/ITO stacked structure, AZO that is ZnO doped with Al, or the likeis used for the pixel electrode 16, for example.

The contact layer 53 and the organic layer 54 are provided with anopening 53 a and an opening 54 a, respectively. A part of the firstconducting portion 31 is exposed from the opening 53 a and the opening54 a. A part 16 c of the opposing region 16 a of the pixel electrode 16contacts the first conducting portion 31 in the opening 53 a and theopening 54 a. Thus, the pixel electrode 16 is electrically connected tothe first conducting portion 31.

A bank layer 40 is provided on the pixel electrode 16 and the organiclayer 54. An insulative and light transmissive material, for example, isused for the bank layer 40. The bank layer 40 is transparent, forexample. An organic resin material, for example, is used for the banklayer 40. A photosensitive acrylic resin, a photosensitive polyimide, orthe like, for example, is used for the bank layer 40. The bank layer 40has an opening 40 a. A part of the non-opposing region 16 b of the pixelelectrode 16 is exposed from the opening 40 a.

The organic light emitting layer 18 is provided on the bank layer 40. Apart 18 a of the organic light emitting layer 18 enters the opening 40a. The organic light emitting layer 18 contacts the non-opposing region16 b of the pixel electrode 16 in the opening 40 a. The organic lightemitting layer 18 is electrically connected to the pixel electrode 16 inthe opening 40 a, for example. The bank layer 40 prevents the opposingregion 16 a from contacting the organic light emitting layer 18. Astacked body having a hole transport layer, a light emitting layer, andan electron transport layer stacked on each other, for example, is usedfor the organic light emitting layer 18. The organic light emittinglayer 18 is light transmissive. The organic light emitting layer 18 istransparent, for example.

The opposite electrode 20 is provided on the organic light emittinglayer 18. A conductive material is used for the opposite electrode 20. Ametal film such as Al and MgAg is used for the opposite electrode 20,for example. The thickness of the opposite electrode 20 is 5 nm or more500 nm or less, for example. In this example, the pixel electrode 16 isserved as an anode and the opposite electrode 20 is served as a cathode.The pixel electrode 16 may be served as a cathode and the oppositeelectrode 20 may be served as an anode.

The light emitting element portion 24 is formed in the non-opposingregion 16 b, for example. In the light emitting element portion 24, avoltage is applied across the pixel electrode 16 and the oppositeelectrode 20 to emit light from the organic light emitting layer 18. Thelight emitted from the organic light emitting layer 18 passes throughthe insulating layer 52, the detecting electrode 50, the gate insulatingfilm 34, and the substrate 10, and goes to the outside. The displaypanel 110 is a lower surface emitting display panel. In the displaypanel 110, the second major surface 10 b is a display surface on whichpictures are displayed. In the display panel 110, the subject to bedetected coming close to the second major surface 10 b is detected, forexample.

A sealing layer 42 is provided on the opposite electrode 20. The sealinglayer 42 suppresses the penetration of impurities, moisture, or thelike, for example. The sealing layer 42 protects the switching element12, the light emitting element portion 24, or the like from moisture orthe like, for example. An insulative material is used for the sealinglayer 42. A silicon oxide film, a silicon oxynitride film, a siliconnitride film, alumina, a tantalum oxide film, or the like is used forthe sealing layer 42, for example.

FIG. 2 is an equivalent circuit diagram illustrating the configurationof the display panel according to the first embodiment.

FIG. 2 schematically illustrates an equivalent circuit diagram of thetouch detection function of the display panel 110.

As shown in FIG. 2, the display panel 110 further includes an amplifiertransistor 60, a select transistor 61, a reset transistor 62, a powersupply line 63, an output signal line 64, a reset power supply line 65,a reset signal line 66, a read signal line 67, and a select signal line68.

The gate of the amplifier transistor 60 is electrically connected to thesource of the reset transistor 62. The drain of the amplifier transistor60 is electrically connected to the source of the select transistor 61.The source of the amplifier transistor 60 is electrically connected tothe read signal line 64.

The gate of the select transistor 61 is electrically connected to theselect signal line 68. The drain of the select transistor 61 iselectrically connected to the power supply line 63. The gate of thereset transistor 62 is electrically connected to the reset signal line66. The drain of the reset transistor 62 is electrically connected tothe reset power supply line 65.

The power supply line 63 supplies a predetermined supply voltage (avoltage of +5 V, for example) to the drain of the select transistor 61.The reset power supply line 65 supplies a predetermined voltage to thedrain of the reset transistor 62.

The detecting capacitor 70 is electrically connected to the gate of theamplifier transistor 60. The detecting capacitor 70 is formed of thepixel electrode 16, the detecting electrode 50, and the insulating layer52, as described above. The capacitance of the detecting capacitor 70 isvaried depending on the presence or absence of the subject to bedetected coming close to the detecting electrode 50 (the second majorsurface 10 b).

A read capacitor 71 and a parasitic capacitance 72 are electricallyconnected to the gate of the amplifier transistor 60. The other end ofthe read capacitor 71 is electrically connected to the read signal line67. The parasitic capacitance 72 is a floating capacitance that appearsin association with the formation of the detecting electrode 50 or thelike, for example. The parasitic capacitance 72 is increased accordingto the area that the pixel electrode 16 overlaps with the detectingelectrode 50, for example.

In the case where a touch manipulation is detected in the display panel110, first, a reset pulse is inputted to the reset signal line 66 toturn the reset transistor 62 into the ON state. When the resettransistor 62 is turned into the ON state, the gate potential of theamplifier transistor 60 is set to a predetermined reference potentialsupplied from the reset power supply line 65.

After setting the gate potential of the amplifier transistor 60 to thereference potential, the reset transistor 62 is turned into the OFFstate. Thus, the gate of the amplifier transistor 60 is turned into anelectrical floating state.

After turning the reset transistor 62 into the OFF state, a select pulseis inputted to the select signal line 68 to turn the select transistor61 into the ON state, and a read pulse is inputted to the read signalline 67. When the read pulse is inputted, the capacitance of the readcapacitor 71 is set to a value corresponding to the read pulse. Thus, apotential corresponding to the capacitance of the detecting capacitor70, the capacitance of the read capacitor 71, the capacitance of theparasitic capacitance 72, and the potential of the read pulse is set tothe gate of the amplifier transistor 60. A current corresponding to thegate potential passes across the drain and the source of the amplifiertransistor 60.

The gate potential of the amplifier transistor 60 when the read pulse isinputted is expressed by Equation (1). In Equation (1), ΔVp is the gatepotential of the amplifier transistor 60. Ct is the capacitance of thedetecting capacitor 70. Cc is the capacitance of the read capacitor 71.Cp is the parasitic capacitance 72 corresponding to the overlap betweenthe detecting electrode 50 and the pixel electrode 16. C0 is theparasitic capacitance of the detecting electrode 50 not depending on theoverlap with the pixel electrode 16. k is a proportionality constant.ΔVc is the voltage amplitude of the read pulse.

$\begin{matrix}{{\Delta\;{Vp}} = {\frac{Cc}{{Cc} + {C\; 0} + {k \times \left( {{Cp} + {Ct}} \right)}} \times \Delta\;{Vc}}} & (1)\end{matrix}$

As shown in Equation (1), the gate potential of the amplifier transistor60 is set according to a capacitance ratio between the capacitance ofthe detecting capacitor 70, the capacitance of the read capacitor 71,and the capacitance of the parasitic capacitance 72. Thus, the gatepotential of the amplifier transistor 60 is varied depending on thecapacitance of the detecting capacitor 70. A current passing across thedrain and the source of the amplifier transistor 60 is varied dependingon the capacitance of the detecting capacitor 70. The capacitance of thedetecting capacitor 70 can be detected by the current passing across thedrain and the source of the amplifier transistor 60. Namely, thepresence or absence of the subject to be detected can be detected.Thereby, the function of detecting a touch manipulation can beimplemented.

The read signal line 64 is electrically connected to the inverting inputterminal of the comparator 73. An output capacitor 74 is electricallyconnected to the read signal line 64 between the amplifier transistor 60and the comparator 73. Thus, a voltage (in the following, referred to asa detection voltage) corresponding to the current passing across thedrain and the source of the amplifier transistor 60 is applied to theinverting input terminal of the comparator 73.

A predetermined threshold voltage is applied to the non-inverting inputterminal of the comparator 73. Consequently, “High” is outputted to theoutput terminal of the comparator 73 in the case where the detectionvoltage is the threshold voltage or less, whereas “Low” is outputted inthe case where the detection voltage is the threshold voltage or more.Thereby, the determination that the subject to be detected is notdetected can be enabled in the case where the output of the comparator73 is “High”. It can be determined that the subject to be detected isdetected in the case where the output of the comparator 73 is “Low”.

FIG. 3 is an equivalent circuit diagram illustrating the configurationof the display panel according to the first embodiment.

FIG. 3 schematically shows an equivalent circuit diagram of the lightemitting function that emits light from the light emitting elementportion 24 of the display panel 110.

As shown in FIG. 3, the display panel 110 further includes a switchtransistor 80, a video signal line 81, a gate line 82, a power supplyline 83, and a capacitor 87.

The source (the first conducting portion 31) of the switching element 12is electrically connected to the anode (the pixel electrode 16) of thelight emitting element portion 24. The drain (the second conductingportion 32) of the switching element 12 is electrically connected to thepower supply line 83 that supplies a supply voltage. The gate (the gateelectrode 33) of the switching element 12 is electrically connected tothe source of the switch transistor 80.

The cathode (the opposite electrode 20) of the light emitting elementportion 24 is electrically connected to a common power supply (a ground,for example). The drain of the switch transistor 80 is electricallyconnected to the signal line 81. The gate of the switch transistor 80 iselectrically connected to the gate line 82.

One end of the capacitor 87 is electrically connected to the gate of theswitching element 12 and the source of the switch transistor 80. Theother end of the capacitor 87 is electrically connected to the source ofthe switching element 12 and the anode of the light emitting elementportion 24.

In the display panel 110, in the case where light is emitted from lightemitting element portion 24, first, a voltage is applied to the gateline 82 to turn the switch transistor 80 into the ON state, a voltagecorresponding to a predetermined video signal (in the following,referred to as a video signal pulse) is applied to the video signal line81, and the voltage is applied to the gate of the switching element 12and the capacitor 87 through the video signal line 81 and the switchtransistor 80 in the ON state. Thus, electric charges corresponding tothe voltage of the video signal line 81 are accumulated in the capacitor87.

After accumulating electric charges in the capacitor 87, the switchtransistor 80 is switched to the OFF state. When the switch transistor80 is switched to the OFF state, a voltage corresponding to the electriccharges accumulated in the capacitor 87 is applied to the gate of theswitching element 12. Thus, a current corresponding to the voltage ofthe gate of the switch transistor 80 passes through the light emittingelement portion 24. Light is emitted from the organic light emittinglayer 18 of the light emitting element portion 24 at the luminancecorresponding to the current.

In the organic EL display panel equipped with the touch detectionfunction, there is a configuration in which the light emitting elementportion 24 and the detecting electrode 50 are disposed side by side. Inthis configuration, in the case where the areas of the pixels are thesame, the area of the light emitting element portion 24 is smaller thanin a display panel without the detection function, causing thedeterioration of image quality. When the area of the light emittingelement portion 24 is smaller in the organic EL display panel, ELlifetime is also shortened.

On the contrary, in the display panel 110 according to the embodiment,the detecting electrode 50 overlaps with the light emitting elementportion 24 when projected onto the first major surface 10 a (the X-Yplane). Thereby, a reduction in the area of the light emitting elementportion 24 and the deterioration of image quality associated with thereduction in the area can be suppressed also in the case of providingthe detection function.

In the display panel 110 according to the embodiment, the semiconductorlayer 35 and the detecting electrode 50 are made of the same amorphousoxide semiconductor. Therefore, the semiconductor layer 35 and thedetecting electrode 50 can be formed in the same process step in thedisplay panel 110, for example. Thereby, the simplification of themanufacturing process steps of the display panel 110 can be enabled, forexample.

FIG. 4 is a graph illustrating the characteristics of the display panelaccording to the first embodiment.

The horizontal axis in FIG. 4 represents a ratio SR of the area of thedetecting electrode 50 to the area of the pixel. The vertical axisrepresents a difference ΔVp1−×Vp2 between a gate potential ΔVp1 of theamplifier transistor 60 in the state in which the subject to be detectedis not detected and a gate potential ΔVp2 of the amplifier transistor 60in the state in which the subject to be detected is detected.

When SR=0, such a state is expressed in which the detecting electrode 50is not provided. When SR=0.5, such a state is expressed in which thedetecting electrode 50 in the area a half of the area of the pixel isprovided. When SR=1, such a state is expressed in which the detectingelectrode 50 in the area the same as the area of the pixel is provided.Namely, the difference ΔVp1−ΔVp2 is the sensitivity to detect thesubject to be detected. The higher the difference ΔVp1−ΔVp2 is, thehigher detection sensitivity is.

In FIG. 4, a solid line expresses the characteristics of the displaypanel 110 according to the embodiment. An alternate long and short dashline expresses the characteristics of a display panel according to areference sample in which the light emitting element portion 24 and thedetecting electrode 50 are disposed side by side. In the configurationof the reference sample, since the light emitting element portion 24 andthe detecting electrode 50 are disposed side by side, it is difficult toform the detecting electrode 50 in the area the same as the area of thepixel. In the display panel 110, since the light emitting elementportion 24 and the detecting electrode 50 are disposed as they overlapwith each other, the detecting electrode 50 in the area the same as thearea of the pixel can also be formed.

As shown in FIG. 4, the sensitivity of the display panel 110 does notexceed a certain value or more, even though the area of the detectingelectrode 50 is increased. It can be considered that this is because thecapacitance Cp of the parasitic capacitance 72 connected to the gate ofthe amplifier transistor 60 is increased as the area of the detectingelectrode 50 is increased and the area of the light emitting elementportion 24 overlapping with the detecting electrode 50 is increased (seeEquation (1) recited above).

However, in the display panel 110, there is no reduction in the area ofthe light emitting element portion 24 caused by the detecting electrode50 (there is no reduction in the aperture ratio). For example, in thedisplay panel 110, the sensitivity in the case where the area of thedetecting electrode 50 is 100% is substantially the same as thesensitivity in the case where the area of the detecting electrode 50 isabout 20% in the configuration of the reference sample, that is, thesensitivity in the case where the area of the light emitting elementportion 24 is reduced by about 20%. For example, the transmittance of acapacitive touch panel equipped later is about 90%. Consequently, inorder to suppress a reduction in the area of the light emitting elementportion 24 to almost the same as the transmittance in the case where thetouch panel is equipped later, it is necessary that a reduction in thearea of the light emitting element portion 24 be 10% or less. Therefore,it can be considered that securing sensitivity by the configuration ofthe display panel 110 is practically effective.

Second Embodiment

FIG. 5 is a schematic view illustrating the configuration of a displaydevice according to a second embodiment.

As shown in FIG. 5, the display device 210 includes a display panel 110,a control unit 120, and a power supply unit 130.

The control unit 120 is electrically connected to the display panel 110to control the operation of a switching element 12 and to detect thecapacitance of a detecting capacitor 70. Namely, the control unit 120controls the light emission of a light emitting element portion 24 andcontrols the detection of a touch manipulation.

The control unit 120 is electrically connected to an output signal line64, a reset signal line 66, a read signal line 67, and a select signalline 68, for example. The control unit 120 inputs various signals to thereset signal line 66, the read signal line 67, and the select signalline 68, and receives a signal outputted from the output signal line 64to control the detection of a touch manipulation.

The control unit 120 is electrically connected to a video signal line 81and a gate line 82, for example. The control unit 120 inputs varioussignals to the video signal line 81 and the gate line 82 to control thelight emission of the light emitting element portion 24, for example.

The control unit 120 receives a video signal through a cable and astorage medium and in a wireless manner, for example. The control unit120 controls the light emission of the light emitting element portions24 included in the display panel 110 corresponding to the inputted videosignal. Thus, the control unit 120 displays a picture corresponding tothe inputted video signal on the display panel 110.

The power supply unit 130 is electrically connected to the display panel110 and the control unit 120. The power supply unit 130 suppliesnecessary power to the display panel 110 and the control unit 120. Thepower supply unit 130 is electrically connected to the power supply line63, the reset power supply line 65, and the power supply line 83, forexample. The power supply unit 130 supplies a supply voltage to thepower supply line 63 and the power supply line 83, for example. Thepower supply unit 130 supplies a predetermined reset power to the resetpower supply line 65, for example.

FIG. 6 is a timing chart illustrating a part of the control of thedisplay device according to the second embodiment.

As shown in FIG. 6, the control unit 120 inputs a video signal pulse,which is a signal to emit light from an organic light emitting layer 18of the light emitting element portion 24 at a predetermined luminance,to the gate of the switching element 12, subsequent to the detection ofthe capacitance of the detecting capacitor 70. The control unit 120detects the capacitance of the detecting capacitor 70 immediately beforeinputting the video signal pulse.

Suppose that the center position on the time base of a single videosignal pulse (a first signal Sg1) is C1 a (a first timing). The centerposition on the time base of the subsequent video signal pulse (a secondsignal Sg1) is C1 b (a second timing). The center position on the timebase between the center position C1 a and the center position C1 b isC2. An interval between the center position C1 a and the center positionC2 is a first interval S1. An interval between the center position C2and the center position C1 b is a second interval S2 (a latter period).The center position of the read pulse inputted to the read signal line67 and the center position on the time base of the select pulse inputtedto the select signal line 68 are C3. The control unit 120 positions thecenter position C3 on the second interval S2. That is, the detecting isperformed in the latter period (the second interval S2).

Therefore, it can be suppressed that the capacitance generated in thedetecting capacitor 70 due to the approach of the subject to be detectedadversely affects electric charges accumulated in the capacitor 87. Thesignal to emit light from the organic light emitting layer 18 is notlimited to the video signal pulse inputted to the video signal line 81.The signal to emit light from the organic light emitting layer 18 may bea given signal to be inputted to the switching element 12 for lightemission.

According to the embodiments, a high-quality display panel having adetection function and a display device can be provided.

In the specification of the application, “perpendicular” and “parallel”refer to not only strictly perpendicular and strictly parallel but alsoinclude, for example, the fluctuation due to manufacturing processes,etc. It is sufficient to be substantially perpendicular andsubstantially parallel.

In the specification of the application, a state in which “a componentis provided on another component” includes a state in which a componentis directly provided on another component as well as a state in which acomponent is provided on another component with a different elementinserted between the component and another component. A state in which“a component is stacked on another component” includes a state in whicha component is stacked on another component to contact each other aswell as a state in which a component is stacked on another componentwith a different element inserted between the component and anothercomponent. A state in which “a component opposes another component”includes a state in which a component directly faces another componentas well as a state in which a component faces another component with adifferent element inserted between the component and another component.

As described above, the embodiments of the invention are described withreference to specific examples.

However, the embodiments of the invention are not limited to thesespecific examples. For example, the specific configurations of thecomponents such as the substrate, the switching element, the pixelelectrode, the organic light emitting layer, the opposite electrode, thedetecting electrode, the insulating layer, the organic layer, thecontact layer and the control unit included in the display panel and thedisplay device are incorporated in the scope of the invention as long asa person skilled in the art appropriately selects components from thepublicly known range to similarly implement the invention for obtainingthe similar effect.

Further, any two or more components of the specific examples may becombined within the extent of technical feasibility and are included inthe scope of the invention to the extent that the purport of theinvention is included.

Moreover, all display panels, and display devices practicable by anappropriate design modification by one skilled in the art based on thedisplay panel, and display device described above as embodiments of theinvention also are within the scope of the invention to the extent thatthe spirit of the invention is included.

Various other variations and modifications can be conceived by thoseskilled in the art within the spirit of the invention, and it isunderstood that such variations and modifications are also encompassedwithin the scope of the invention.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A display panel comprising: a substrate having amajor surface, the substrate being light transmissive; a switchingelement provided on the major surface and including a semiconductorlayer; a pixel electrode provided on the major surface and electricallyconnected to the switching element, the pixel electrode being lighttransmissive; an organic light emitting layer provided on the pixelelectrode; an opposite electrode provided on the organic light emittinglayer; a detecting electrode provided between the substrate and at leasta part of the pixel electrode and including at least one elementincluded in the semiconductor layer, the detecting electrode being lighttransmissive; an insulating layer provided between the pixel electrodeand the detecting electrode, the insulating layer being lighttransmissive, the pixel electrode, the detecting electrode, and theinsulating layer forming a detecting capacitor; an amplifier transistorhaving a gate electrode, the gate electrode being electrically connectedto the detecting capacitor; and an output signal line being electricallyconnected to the amplifier transistor, the amplifier transistor passinga current depending on a capacitance of the detecting capacitor to theoutput signal line, wherein the semiconductor layer and the detectingelectrode each independently comprise an amorphous oxide which comprisesat least one of In, Ga, and Zn.
 2. The panel according to claim 1,wherein a difference between a distance between the detecting electrodeand the substrate along a first direction perpendicular to the majorsurface and a distance between the semiconductor layer and the substratealong the first direction is 10 nm or less.
 3. The panel according toclaim 1, wherein a thickness of the semiconductor layer is 10 nm or moreand 100 nm or less.
 4. The panel according to claim 1, wherein theinsulating layer includes an organic layer, and a thickness of theorganic layer along a first direction perpendicular to the major surfaceis 1 μm or more 10 μm or less.
 5. The panel according to claim 1,wherein the insulating layer includes a contact layer contacting thedetecting electrode, and the contact layer includes at least one of asilicon oxide film, a silicon oxynitride film, and a silicon nitridefilm.
 6. The panel according to claim 5, wherein the contact layerincludes hydrogen at a concentration of 1×10¹⁹ atoms/cm³ or more.
 7. Thepanel according to claim 5, wherein a thickness of the contact layer is100 nm or more and 200 nm or less.
 8. The panel according to claim 1,wherein the substrate includes at least one of a polyimide resin and anaramid resin, and the substrate is flexible.
 9. The panel according toclaim 1, wherein the opposite electrode includes at least one of Al andMgAg.
 10. The panel according to claim 1, wherein a thickness of theopposite electrode is 5 nm or more 500 nm or less.
 11. The panelaccording to claim 1, wherein the pixel electrode includes one of anITO, an ITO/Ag/ITO stacked structure, and ZnO including Al.
 12. Thepanel according to claim 1, wherein the switching element includes agate electrode provided on the major surface, a gate insulating filmprovided on the gate electrode, the semiconductor layer provided on thegate insulating film, the semiconductor layer including a first region,a second region apart from the first region, and a third region providedbetween the first region and the second region, a first conductingportion electrically connected to the first region and the pixelelectrode, and a second conducting portion provided apart from the firstconducting portion and electrically connected to the second region. 13.The panel according to claim 12, wherein the detecting electrode isprovided on the gate insulating film.
 14. The panel according to claim12, wherein the switching element further includes a channel protectionfilm provided at least on the third region.
 15. The panel according toclaim 1, further comprising a sealing layer provided on the oppositeelectrode, the sealing layer including at least one of a silicon oxidefilm, a silicon oxynitride film, a silicon nitride film, alumina, and atantalum oxide film.
 16. The panel according to claim 1, wherein thesemiconductor layer and the detecting electrode each independentlycomprise an amorphous oxide selected from the group consisting of anIn—Ga—Zn—O oxide semiconductor, an In—Ga—O oxide semiconductor, and anIn—Zn—O oxide semiconductor.
 17. The panel according to claim 1, whereinthe semiconductor layer and the detecting electrode each comprise thesame amorphous oxide.
 18. A display device comprising: a display panelincluding: a substrate having a major surface, the substrate being lighttransmissive; a switching element provided on the major surface andincluding a semiconductor layer; a pixel electrode provided on the majorsurface and electrically connected to the switching element, the pixelelectrode being light transmissive; an organic light emitting layerprovided on the pixel electrode; an opposite electrode provided on theorganic light emitting layer; a detecting electrode provided between thesubstrate and at least a part of the pixel electrode and including atleast one element included in the semiconductor layer, the detectingelectrode being light transmissive; an insulating layer provided betweenthe pixel electrode and the detecting electrode, the insulating layerbeing light transmissive, the pixel electrode, the detecting electrode,and the insulating layer forming a detecting capacitor; an amplifiertransistor having a gate electrode, the gate electrode beingelectrically connected to the detecting capacitor; an output signal linebeing electrically connected to the amplifier transistor, the amplifiertransistor passing a current depending on a capacitance of the detectingcapacitor to the output signal line; and a control unit configured tocontrol an operation of the switching element to control a light emittedfrom the organic light emitting layer and configured to detect acapacitance of a detecting capacitor formed of the pixel electrode, thedetecting electrode, and the insulating film, wherein the semiconductorlayer and the detecting electrode each independently comprise anamorphous oxide which comprises at least one of In, Ga, and Zn.
 19. Thedevice according to claim 18, wherein the control unit inputs a signalto emit the light from the organic light emitting layer to the switchingelement, subsequent to the detecting the capacitance.
 20. The deviceaccording to claim 19, wherein the control unit is configured to input afirst signal at a first timing to emit the light to the switchingelement; and input a second signal at a second timing to emit the lightto the switching element, the second timing is after the first timing,and the detecting is performed in a latter period between the firsttiming and the second timing.
 21. The display device according to claim18, wherein the semiconductor layer and the detecting electrode eachindependently comprise an amorphous oxide selected from the groupconsisting of an In—Ga—Zn—O oxide semiconductor, an In—Ga—O oxidesemiconductor, and an In—Zn—O oxide semiconductor.
 22. The displaydevice according to claim 18, wherein the semiconductor layer and thedetecting electrode each comprise the same amorphous oxide.